On February 28th, 2017, a “cockup at Amazon facility in Virginia, US” caused its S3 cloud storage to fail.
This fault led to “major websites and services - including Imgur, Medium, Trello, Yahoo webmail, the Docker Registry Hub.. falling offline, losing images, or left running like treacle. Basically, that outage “knackered half the internet, it seems, because it all relies on S3 to store data online”.
Just to stress: this is one S3 region that has become inaccessible, yet web apps are tripping up and vanishing as their backend evaporates away.